The Justice Department's top internal investigator yesterday sharply criticized the White House and Attorney General Benjamin R. Civiletti for delaying the recommended firings of a Hispanic U.S. attorney and a U.S. marshal in Kentucky.

Michael E. Shaheen Jr., head of the office of professional responsibility, which monitors the ethical conduct of department employes, called the delays "inexcusable" and said they called into question "the very integrity of the Department of Justice."

Though no names were mentioned in Shaheen's report of his office's 1979 activities, it is clear that his barbs at the White House involved a case against Herman Sillas Jr., the U.S. attorney in Sacramento.

In his report, Shaheen said, "We cannot overstate our concern that, unless this matter is concluded quickly and definitively, the very integrity of the Department of Justice is likely to be called into serious question. Inquiries involving high-level officials should be handled as expeditiously and unswervingly as are matters involving other personnel with the Department of Justice, and the handling of this matter . . . appears to us inexcusable because we can see no appropriate motivation for the delays permitted by White House personnel."

Sillas held an extraordinary news conference last week to criticize Justice's case against him. He reportedly failed two lie detector test about taking an alleged $7,500 bribe from a California man in 1974.

The criticism of Civiletti stemmed from his handling of the recommended dismissal of Robert L. Wright, the U.S. marshal in Kentucky, whose daughter is married to the son of Sen. Walter (Dee) Huddleston (D-Ky.).

Both Civiletti and White House officials defended their actions in the two cases yesterday.

Wright submitted his resignation in mid June, more than 10 months after his firing was first recommended and more than four months after Civiletti had White House approval for the dismissal.

Shaheen's report said the marshal had engaged in "gross mismanagement, abuse of authority and total disregard of regulations." He said "it is difficult to understand why this situation drags on, depite clear presidential authority to proceed."

Civiletti told reporters yesterday that "sometimes I cannot act sooner because of the press of other business."

In the Sillas case, Michael Cardozo, an attorney in the office of White House counsel Lloyd Cutler, said yesterday that a final recommendation to the president on the prosecutor's job will be made soon.

He denied Shaheen's comment that it was "highly irregular" to let Sillas' attorney conduct a separate investigation of the matter. "It's fairly irregular for the department to recommend a prosecutor be dismissed," Cardozo said. "That's a gratuitous statement."

Cardozo said Sillas requested more time to state his side of the case because he felt he didn't get a fair hearing by the department's internal investigators. An official of the deputy attorney general's office, which recommended the dismissal, was consulted continually and given a chance to respond to Sillas' rebuttal of the charges, he added.

Cardozo rejected any suggestion that the delay was caused by administration sensitivity to Sillas' supporters in the Hispanic community, an important voting block.

Shaheen's report also criticized the "lenient and convenient 'punishments'" of two Justice officials who "subverted" the department's hiring policies for personal reasons. One official was allowed to transfer to another city with no loss in pay, and the other was permitted to serve a two-week suspension over the Christmas holidays.

Shaheen recommended in his report that there be a departmentwide schedule of suggested punishments, because of disarities which make the system "appear to be unfair, arbitrary and capricious." For instance, he noted that two FBI agents, married but not to each other, were fired because of a romantic relationship, while an undercover agent who got drunk and revealed his identity and mission in a restaurant was merely suspended for 30 days.

FBI Director William H. Webster has said he intends to keep out of employe's private lives in disciplinary matters. But a spokesman said the fired agents were not dismissed merely for the sexual liaison but because they were in training as new agents and had been warned to stop the relationship.

Other examples of the human frailties of department employes also are referred to in the report.

A Roman Catholic priest who, while a prison chaplain, pleaded guilty to federal charges of receiving a free Las Vegas vaction trip arranged by an inmate who was an oranized crime figure.

An FBI agent who resigned after engaging in homosexual conduct with a minor.

A deputy U.S. marshal who was suspended after using a government car to visit a massage parlor and then charging overtime for the time he spent there.

Another deputy marshal who was suspended after having sex with a prostitute and paying by check -- "apparently having first established his creditworthiness by displaying his credentials and service revolver."

A law clerk in a U.S. attorney's office who was convicted of stealing FBI documents and selling them for $50,000 to the subject of a criminal investigation.